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POE cables - I'm going insane!

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Joe Shmoe

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Please can someone shed some light on this before I go insane!

Wiring up some cctv cameras using POE. All cameras work when using pre-fabricated cat5e cables. The camera LEDs light up inside, but they won't actually work. Its definitely my home-made cables that are the issue, but for the life of me I can't see why!

Anyway...

I've got a tester and measured the pre-fab cables against my own. They're identical in every aspect according to the tester (photo attached).

Now, I was under the impression that it doesn't matter what order you crimp the 8 wires into the RJ45, so long as they're identical at the other end (which mine were according to the tester).

I've just had another go (after about a dozen unsuccessful cables) and for some reason when I use the correct order of colours (orange+white /orange / green+white /blue /blue+white /green/ brown+white /brown) it works.

Have I just crimped better than my previous efforts, or is there an actual reason why this works but using my own order of colours wouldn't? The only thing I could think of is electronic signal loss because certain colours run closer to others in the wire.

I don't understand what difference the colour sequence makes so long as each wire is in the same order at each end of the cable?

Any guidance gratefully received!
 

Sandyn

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I assume you are maintaining the twisted pairs when you wire it with your colour system?
 

Joe Shmoe

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Yes, I was using this...

Blue, Blue+White, Brown, Brown+white, Green, Green+White, Orange, Orange+white.
 

Rorton

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You have to wire to the standard as you found out when your cable works, in essence it’s a balanced cable

use 568b

further down this article expains the reasoning on the cables and why you don’t just group the same pairs together.


nice one for getting it working though, they can be a pain sometimes.
 

Old.bodger

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Orange white/ orange/ green white/ blue/ blue white/ green / brown white/ brown.
starting from the left hand pin when viewed above with the retaining clip underneath.

Works for me. Some makes of RJ45 plugs are a nightmare. The type that have a cable sequence bar that you fill first are good if you don’t do them regularly.

1618086292749.jpeg
 

nickds1

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Also note that the RJ45 plugs are designed for stranded (so-called patch) cable and not for solid core (infrastructure) cable. When used on solid core they are hopelessly unreliable. Only sockets or patch panels are designed to take solid cable - they use a different type of insulation displacement connection (pinches the solid core rather than the plugs which stab into the middle of the strands).

As stated before, use only T-568B and do not mix standards. Note also that not all PoE is the same - there are a few standards and you need to have a compatible PoE injector or switch for the driven device.

Also keep the twisted pairs short when stripping back the cable and keep the twist up to as close as you can to the crimp if you want error free transmission and to get close to the actual specs for cat5e or cat6. On a socket, the maximum length outside a strip should be about 2cm.

Most "examples" on the www are pretty dire. "It seems to work" is not the same as "it's a connection to cat5e standards".
 
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Spectric

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I think you are learning that frequency has a major impact on interconnects. Once you reach a high enough frequency the signal on say a PCB will behave just like trying to get a scalectrix car round a bend to fast, it just keeps going straight.
 

--Tom--

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It’s ghost work to me. Whole house is cat 6 and took a year of fiddling to work. Science did not seem to apply
 

Jake

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Orange white/ orange/ green white/ blue/ blue white/ green / brown white/ brown.
starting from the left hand pin when viewed above with the retaining clip underneath.

Works for me. Some makes of RJ45 plugs are a nightmare. The type that have a cable sequence bar that you fill first are good if you don’t do them regularly.

View attachment 108051
Those look good, never come across those, but I just found (and immediately bought) the set up for the feed-thru type- a revelation.
 

Spectric

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Always buy top brand cable not the stuff your local shed sells, and decent connectors because they may all look like just a cheap & nasty bits of plastic but there are good & bad. Cable well Huber & Suhner are reputable for all aspects of RF, microwave and optical to name a few.
 

flying haggis

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Orange white/ orange/ green white/ blue/ blue white/ green / brown white/ brown.
starting from the left hand pin when viewed above with the retaining clip underneath.

Works for me. Some makes of RJ45 plugs are a nightmare. The type that have a cable sequence bar that you fill first are good if you don’t do them regularly.

View attachment 108051
you can also get plugs that allow you to poke the cables out the "front" . it means you dont have to get the cut length exactly right and to pull the cable sheath into the grip position before crimping.
then you trim the excess cable sticking out the front off.
search for pass through rj45. i have used them and they do work

and as spectric said use only solid copper cable not copper covered aluminium. cca.
 
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rs6mra

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as has been said use T-568B
ensure that your cable is not solid core but stranded
also, check the RJ45 to make sure you are using the right one for Cat5e
cable quality also matters and avoid by all cost those marked CCA or CCE certified or similar. Buy from a reputable company.
If you are using solid core then terminate to a patch panel and wall plate and then use a patch cable
 

eddycarroll

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I was using this...
Blue, Blue+White, Brown, Brown+white, Green, Green+White, Orange, Orange+white.
As others mentioned, you won't go wrong if you stick with the official T-568B wiring order.

The ordering you listed above won't work reliably over more than a couple of metres, because despite how it appears, your signals are being crossed. The equipment your cables plug into are expecting this layout:

Pins 1 & 2 - orange/white & orange - Data TX+ / TX-
Pins 3 & 6 - green/white & green - Data RX+ / RX-
Pins 4 & 5 - blue & blue/white - DC+ (POE)
Pins 7 & 8 - brown/white & brown - DC- (POE)

With your custom arrangement, pin 3 is Brown and pin 6 is Green+White, so you are splitting the Data RX signal across the brown and green pairs. Not only are you losing the protection from crosstalk and external interference, the brown and green pairs have different twist ratios so the signal on Brown won't arrive at the far end at quite the same time as its matching signal on Green+White. The longer the cable, the more significant this becomes.

(The above is for 100BASE-T links, which covers most IP cameras. Modern cameras that support PoE-over-Gigabit are even more demanding, but again will be fine if you stick to the T-568B ordering and follow good installation practise.)

nickds1 mentioned that standard RJ45 connectors are intended for stranded cable and won't work reliably on solid-core copper. This is true, but you can buy RJ45 connectors that work fine on solid copper - the teeth on each pin are offset so that one straddles either side of the copper wire, ensuring a good connection. You just need to be aware of which type you are working with and not assume one size fits all.
 
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Cirks

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Have real fun with thick coated Cat6e external cable....then you know what a battle is with RJ45 plugs (direct Poe to cctv rather than via patch which would have been more sensible except the switch from the patch would have needed to be Poe)
 

nickds1

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nickds1 mentioned that standard RJ45 connectors are intended for stranded cable and won't work reliably on solid-core copper. This is true, but you can buy RJ45 connectors that work fine on solid copper - the teeth on each pin are offset so that one straddles either side of the copper wire, ensuring a good connection. You just need to be aware of which type you are working with and not assume one size fits all.
Yes, you can get them but they are very expensive. The correct way is to terminate in a socket and then use a proper stranded patch cable from then on in.
  • All devices have female connectors.
  • All infrastructure cable is female to female and solid core. It's not designed to be moved around and has minimum bend radius rules that must be observed
  • All patch cables are male to male and stranded.
  • All wiring standards to T-568B
Stick to the above and you won't go wrong (hah!)
 

DBT85

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Every cable (long runs to sockets or patch panel and patch cables) in my house is using solid core and the only time I've ever had an issue with an rj45 is when I cocked it up. Didn't even know stranded cable existed and I've been making cables up for 25 years now 😂.

Learn something new every day.

I guess the only ones I have that aren't solid core are the patch leads that comes with everything. Only using a few of those though.

I really do need to get some Swann cameras setup here. Want it all stored on site, no need for it all to disappear off to amazon or whomever else for a fee every month for the next 10 years.

Orange white/ orange/ green white/ blue/ blue white/ green / brown white/ brown.
starting from the left hand pin when viewed above with the retaining clip underneath.

Works for me. Some makes of RJ45 plugs are a nightmare. The type that have a cable sequence bar that you fill first are good if you don’t do them regularly.

View attachment 108051
Now that's cheating.
 
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